Name: how depth changes fluid pressure
Uploaded: 2023-09-22T11:49:33.000Z
Duration: 1 min 14 s
Channel: JoVE

压强定义为单位面积上的力的大小。对于不可压缩流体，该力可以用流体的单位重量或密度来表示。
考虑水中的四个点。在距水面相同深度处，所有点的压强均相同，但在较浅深度处压强较小。压强随水面深度的增加而线性增大。
根据帕斯卡定律，不可压缩静止流体中任意给定点的压强在所有方向上均相同。
假设一个单位宽度的楔形无穷小流体微元。每一侧面上的力表示为压力与面积的乘积。
由于液体处于静止状态，作用力的水平分量和垂直分量的总和应为零。
取水平分量并利用三角关系，可将方程简化，得到 px 等于 ps。
同理，考虑垂直分量时，可将方程简化，得到 py 等于 ps。&#160;
因此，任意一点的压力在所有方向上都是相同的。

流体压力

在机械工程中，流体压力在设计利用液体流动的系统（如液压系统、泵和阀门）中起着至关重要的作用。在设计这些系统时，工程师必须确保它们能够承受由流体压力所产生的力量，以避免其发生损坏或故障。 根据帕斯卡定律，静止的流体会在所有方向上产生相等的压力。这个压力以单位面积的力来进行衡量，其大小取决于流体的比重或质量密度以及测量点距离流体表面的深度。我们可以用数学关系式p = ρgz来表示这种关系，其中ρ是流体密度，g是重力加速度，z是深度。 需要注意的是，如上所述的方程式适用于不可压缩流体，如大多数液体，但不适用于气体，气体的密度会随温度和压力的改变而发生变化。如果要理解这个方程式是如何应用于液体中，则需要思考一下位于水中的三个点。在距离表面相同的深度处，三个点的压力是相同的。然而，在较浅的深度出则压力较低。随着与表面距离的增加，其压力也会随之线性增加。

在机械工程中，流体压力在设计利用液体流动的系统（如液压系统、泵等）时起着关键作用。

Education

教育

JoVE Core

Mechanical Engineering

机械工程

Unit 1

第一单元

Center of Gravity and Centroid

重心与形心

KEY TERMS AND CONCEPTS

关键术语与概念

Fluid Pressure

how depth changes fluid pressure

Fluid pressure changes with depth in liquids used in engineering systems. It matters in hydraulic systems, pumps, and valves, where the forces from moving and resting fluid must be considered to prevent damage or failure.

For a fluid at rest, Pascal’s law says the pressure is equal in all directions. Pressure is force per unit area. Its size depends on the fluid’s specific weight, or mass density, and on how deep the measurement point is below the fluid surface.

This relationship can be written as p = ρgz. In this equation, ρ is fluid density, g is the acceleration due to gravity, and z is depth. The equation applies to incompressible fluids, such as most liquids, but not to gases, because gas density can change greatly with temperature and pressure.

The pattern is easy to see in water. If three points are at the same depth, their pressure is the same. A point closer to the surface has lower pressure. As depth increases, pressure rises in a linear way.

How Depth Changes Fluid Pressure

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Fluid pressure changes with depth in liquids used in engineering systems. It matters in hydraulic systems, pumps, and valves, where the forces from moving and resting fluid must be considered to prevent damage or failure. For a fluid at rest, Pascal’s law says the pressure is equal in all directions. Pressure is force per unit area. Its size depends on the fluid’s specific weight, or mass density, and on how deep the measurement point is below the fluid surface. This relationship can be...

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key terms and concepts

Explore how fluid pressure changes with depth, why Pascal’s law matters, and how the equation p = ρgz describes pressure in liquids like water.

How Depth Changes Fluid Pressure | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

How Depth Changes Fluid Pressure

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